Patent GB-760057-A (GB)
Title: Improvements in the production of carboxylic acids and their esters
IPC: C07C51/12
Filed: 1954-04-07
Abstract: A polyester of adipic acid and butanediol is produced by reacting 1,4-butanediol with carbon monoxide under 700 atmospheres pressure at a temperature in the range 180 DEG  to 220 DEG  C. in the presence of a catalyst comprising cobalt adipate, 1,4-dichlorobutane and adipic acid pyrrolidide.  In general, ethylene glycol, propylene glycol and other dihydric alcohols having 2 to 6 carbon atoms are converted into esters by reaction with carbon monoxide at elevated temperature and pressure in the presence of a catalyst comprising a cobalt salt, a halogen and an N-mono or N-disubstituted carboxylic acid amide.ALSO:Carboxylic acids and their esters are produced by the reaction of an alcohol with carbon monoxide at elevated temperature under superatmospheric pressure in the presence of a catalyst comprising a cobalt salt, a halogen and an N-mono or N-di-substituted carboxylic acid amide.  The cobalt salt is preferably a salt of a carboxylic acid such as a fatty acid, or a cycloaliphatic, aromatic or resin acid.  A salt of the acid formed in the process is most preferred.  The halogen, preferably chlorine or bromine, may be in elemental form but, preferably, chlorinated or brominated hydrocarbons containing up to 6 carbon atoms are used.  It is preferred to use an amide of the carboxylic acid formed in the process wherein the amide radical is derived from an amine the alkyl radical of which corresponds to the alcohol used.  Other suitable amides are acetic acid mono- and di-methyl amide, diethyl amide or dibutyl amide, acetic acid pyrrolidide, propionic acid hexamethylene imide, diacetyl methyl amine, methylurea, pyrrolidone, methyl pyrrolidone or dimethyl formamide.  The reaction may be effected at temperatures between 70 DEG  and 250 DEG  C., preferably between 170 DEG  and 230 DEG  C., although temperature up to 300 DEG  C. may be used.  Pressure above 50 atmospheres are used, preferably in the range between 200 and 700 atmospheres.  The carbon monoxide may be pure or may contain nitrogen, methane, carbon dioxide and/or hydrogen.  Suitable alcohols are saturated mono- and dihydric alcohols of up to 6 carbon atoms such as methanol, ethanol, propanols, butanols, pentanols, ethylene glycol, propylene glycol and butanediols. Araliphatic or cycloaliphatic alcohols may also be used. The alcohols are preferably unsubstituted and are free from unsaturation.  The amounts of catalyst and halogen used are preferably each between 0.1 and 15 per cent by weight of the starting material.  Between 10 and 100 per cent by weight of amide, calculated on the alcohol, is used.  Solvents such as hydrocarbons, esters, phenols, ethers, N-alkyl lactams, or the ester reaction products, may be used.  The process may be batchwise or continuous.  It is preferred to interrupt the reaction when only a part of the starting material is converted, separate the unchanged material and recycle it to the reactor. The products may be separated by distillation and the catalyst remaining in the residue may be used again without purification. Detailed examples are given in which carbon monoxide is reacted with methanol to give acetic acid, methyl acetate and acetic anhydride, n-butanol to give valeric acid and n-butyl valerate, sec.-butanol to give iso-valeric acid and iso-butyl iso-valerate, t-butanol to give pivalic acid and t-butyl pivalate, benzyl alcohol to give phenyl acetic acid, and 1,4-butanediol to give a polyester from adipic acid and butanediol (see Group IV (a)).  In the catalysts, the cobalt salt is cobalt acetate, valerate, isovalerate, or adipate, or cobalt phenyl acetate; the halogen is in the form of ethyl bromide or methyl, ethyl, n-butyl, sec.-butyl, t-butyl or benzyl chloride or 1,4-dichlorobutane; the amide is dimethyl acetamide, dimethyl urea, diacetyl methyl amine, acetic acid di-n-butylamide, isovaleric acid di-isobutyl amide, acetic acid di-t-butylamide, phenylacetic acid benzyl amide, adipic acid pyrrolidide or acetyl p-toluidide.ALSO:Catalysts, for the preparation of carboxylic acids and esters by reaction of carbon monoxide with alcohols (see Group IV(b)), comprise a cobalt salt, a halogen and an N - mono - or N di - substituted carboxylic acid amide.  The cobalt salts may be salts of carboxylic acids such as fatty acids cycloaliphatic, aromatic or resin acids.  Preferably salts of the carboxylic acids formed in the process are used.  The halogen, preferably chlorine or bromine, may be in elemental form but preferably chlorinated or brominated hydrocarbons containing up to 6 carbon atoms are used.  It is preferred to use an amide of the carboxylic acid formed in the process wherein the alkyl substituents of the amino group correspond to the alcohol starting material. Suitable amides are acetic acid mono - and dimethyl amide, diethyl amide or dibutyl amide, acetic acid pyrrolidide, propionic acid hexamethylene imide, diacetyl methyl amine, methyl urea, pyrrolidone, methyl pyrrolidone, or dimethyl formamide.  The amount of cobalt in the form of salts and the amount of halogen, are preferably each between 0.1 and 15 per cent by weight of the alcohol, and the amount of amide is between 10 and 100 per cent by weight of the alcohol.  In examples, the cobalt salt is cobalt acetate, valerate, isovalerate, or adipate or cobalt phenyl acetate; the halogen is in the form of ethyl bromide or methyl, ethyl, n - butyl, sec - butyl, t - butyl or benzyl chloride, or 1, 4 dichlorobutane; the amide is dimethyl acetamide, dimethyl urea, diacetyl methyl amine, acetic acid, di - n - butylamide or di - t - butylamide, isovaleric acid di - isobutylamide, phenyl acetic acid benzylamide, adipic acid pyrrolidide or acetyl p - toluidide; and the resultant mixed product constituting the catalyst is placed in the pressure vessel in which the reaction takes place.